Question 1

Which of the following best explains why proteins are considered polymers of amino acids?

Accepted Answer

Proteins are formed by the covalent linkage of amino acids via peptide bonds, creating long chains with specific sequences.

Question 2

Which of the following amino acids is classified as aromatic?

Accepted Answer

Phenylalanine

Question 3

A Ramachandran plot is used to:

Accepted Answer

Visualize the allowed values of $$\phi$$ and $$\psi$$ angles in a polypeptide backbone.

Question 4

Which of the following is a correct statement about the secondary structure of proteins?

Accepted Answer

The $$\alpha-$$helix is stabilized by hydrogen bonds between the carbonyl oxygen of one amino acid and the amide hydrogen four residues ahead.

Question 5

Which of the following best describes the quaternary structure of a protein?

Accepted Answer

The arrangement and interaction of multiple polypeptide chains in a multi-subunit protein.

Question 6

Which of the following is a major class of protein function?

Accepted Answer

Transport proteins

Question 7

The dissociation constant $$K_d$$ for a protein-ligand interaction is defined as:

Accepted Answer

$$K_d = \frac{[P][L]}{[PL]}$$

Question 8

Which of the following statements about hemoglobin is correct?

Accepted Answer

Hemoglobin exhibits cooperative binding of oxygen, resulting in a sigmoidal oxygen binding curve.

Question 9

Which of the following is a function of enzymes as biological catalysts?

Accepted Answer

Enzymes lower the activation energy ($$\Delta G$$^{\ddagger}$$) of a reaction, increasing the rate without being consumed.

Question 10

Which of the following mechanisms is NOT a common enzyme catalytic strategy?

Accepted Answer

Photocatalysis

Question 11

A mutation in hemoglobin that increases its affinity for 2,3-bisphosphoglycerate (2,3-BPG) would most likely:

Accepted Answer

Decrease hemoglobin's affinity for oxygen, facilitating oxygen release in tissues.

Question 12

Which of the following statements about the specificity of serine proteases is correct?

Accepted Answer

Chymotrypsin prefers to cleave peptide bonds adjacent to aromatic amino acids due to the hydrophobic nature of its binding pocket.

Question 13

Which of the following best describes the effect of a competitive inhibitor on enzyme kinetics?

Accepted Answer

It increases the apparent $$K_m$$ but does not affect $$V_{max}.$$

Question 14

Which of the following statements about protein folding is correct?

Accepted Answer

Protein folding is driven by the hydrophobic effect, where nonpolar amino acids aggregate to minimize contact with water.

Question 15

Which of the following is a correct statement about the Michaelis-Menten equation?

Accepted Answer

The initial velocity $$v_0 is $$given by $$v_0$$ = \frac{V_{max}[S]}{K_m + [S]}$$

Question 16

Which of the following amino acids is most likely to be found on the surface of a globular protein?

Accepted Answer

Aspartate

Question 17

Which of the following statements about the role of metal ions in enzyme catalysis is correct?

Accepted Answer

Metal ions can stabilize negative charges and participate directly in catalysis.

Question 18

Which of the following best explains the effect of pH on enzyme activity?

Accepted Answer

Enzyme activity is highest at an optimal pH, and deviations can alter the ionization state of active site residues, reducing activity.

Question 19

Which of the following statements about the thermodynamics of protein folding is correct?

Accepted Answer

Protein folding is favored when the change in Gibbs free energy $$\Delta G is $$negative.

EXAM 2: Study Guide

Study Guide - Practice Questions